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Re: Go SDK: bad parameter type for reflect.methodValueCall: func(Record)


Hi Eduardo,

 You're not doing anything wrong. Maps are currently not classified as a valid data type by the type checker, but perhaps they should be.

       https://github.com/apache/beam/blob/6889792b994e1418ae73940198eb8767950287b5/sdks/go/pkg/beam/core/typex/class.go#L97

Please feel free to open a bug. As a less-than-convenient workaround, you can use a slice.

Thanks,
 Henning 

On Mon, Jun 18, 2018 at 2:10 PM eduardo.morales@xxxxxxxxx <eduardo.morales@xxxxxxxxx> wrote:
I have the following code:

type Record struct {
       Timestamp time.Time
       Payload   string
}

type processFn struct {
        // etc...
}

func (f *processFn) ProcessElement(ctx context.Context, data []byte, emit func(Record)) {
         // etc..
         emit(someRecord)
         // etc...
}

Which is eventually invoked as:
beam.ParDo(scope, &processFn{}, pcoll)

This seems to work fine using the direct runner until I add a map to the Record struct as follows:

type Record struct {
        Timestamp    time.Time
        Payload      string
        Labels       map[string]string
}

Then I get the error mentioned in the subject line.

My questions are:
- Are maps illegal? What is a legal structure? or
- Is the feature yet to be implemented? or
- Am I doing something wrong? Am I failing to setup my pipeline correctly?

Thanks for your help.